Residual Gas and Dust around Transition Objects and Weak T Tauri Stars
Abstract
Residual gas in disks around young stars can spin down stars, circularize the orbits of terrestrial planets, and whisk away the dusty debris that is expected to serve as a signpost of terrestrial planet formation. We have carried out a sensitive search for residual gas and dust in the terrestrial planet region surrounding young stars ranging in age from a few to ∼10 Myr. Using high-resolution 4.7 μm spectra of transition objects (TOs) and weak T Tauri stars, we searched for weak continuum excesses and CO fundamental emission, after making a careful correction for the stellar contribution to the observed spectrum. We find that the CO emission from TOs is weaker and located farther from the star than CO emission from nontransition T Tauri stars with similar stellar accretion rates. The difference is possibly the result of chemical and/or dynamical effects (I.e., a low CO abundance or close-in low-mass planets). The weak T Tauri stars show no CO fundamental emission down to low flux levels (5 × 10-20 to 10-18 W m-2). We illustrate how our results can be used to constrain the residual disk gas content in these systems and discuss their potential implications for star and planet formation.
Data presented herein were obtained at the W. M. Keck Observatory from telescope time allocated to the National Aeronautics and Space Administration through the agency’s scientific partnership with the California Institute of Technology and the University of California. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation.- Publication:
-
The Astrophysical Journal
- Pub Date:
- February 2017
- DOI:
- 10.3847/1538-4357/aa5c3c
- arXiv:
- arXiv:1701.06758
- Bibcode:
- 2017ApJ...836..242D
- Keywords:
-
- circumstellar matter;
- infrared: stars;
- protoplanetary disks;
- stars: formation;
- stars: pre-main sequence;
- techniques: spectroscopic;
- Astrophysics - Solar and Stellar Astrophysics;
- Astrophysics - Earth and Planetary Astrophysics;
- Astrophysics - Astrophysics of Galaxies
- E-Print:
- 40 pages, 12 figures, 3 tables, accepted for publication in ApJ